Thermoplastic shielded glass bottle with highly roughened surface

ABSTRACT

A container comprising an inner glass receptacle and a closely adhering exterior protective sheath substantially covering said receptacle. The exterior protective sheath is comprised of a shape-retaining, preferably thermoplastic resin adapted to restrain and retain glass fragments should the glass receptacle be broken. The sheath is further provided with a substantially roughened surface which exhibits a surface elevation variance from the mean thickness of the sheath by between about 50 and 120 percent. Such surface characteristics in addition to their functional effects also produce interesting and attractive optical characteristics and substantially reduce the light transmittance thereof.

United States Patent 1 Campagna 1 June 11, 1974 1 1 THERMOPLASTIC SHIELDED GLASS BOTTLE WITH HIGHLY ROUGHENED [58] Field of Search..... 215/1 R, l C, 12 R, DIG. 6; 1l7/17.5, 18, 33.3, 37 R, 41; 161/2, 116, 119, 124, 164, 117; 65/60; 313/110, 116, 117; 356/108, 109; 350/164, 165; 431/94 [56] References Cited UNITED STATES PATENTS 596,304 12/1897 Paquette 215/12 R 2,946,911 7/1960 Malinowski et a1 313/116 3,006,780 10/1961 Shaffer 2l5/D1G. 6 3,067,352 12/1962 Vodicka et a1. 313/116 3,178,049 4/1965 Cottet 215/1 C 3,200,280 8/1965 Thau et a1 [17/41 Primary Examiner-Wi1liam 1. Price Assistant Examiner-Stephen Marcus [5 7 ABSTRACT A container comprising an inner glass receptacle and a closely adhering exterior protective sheath substantially covering said receptacle. The exterior protective sheath is comprised of a shape-retaining, preferably thermoplastic resin adapted to restrain and retain glass fragments should the glass receptacle be broken. The sheath is further provided with a substantially roughened surface which exhibits a surface elevation variance from the mean thickness of the sheath by between about 50 and 120 percent. Such surface characteristics in addition to their functional effects also produce interesting and attractive optical characteristics and substantially reduce the light transmittance thereof.

6 Claims, 3 Drawing Figures THERMOPLASTIC SHIELDED GLASS BOTTLE WITH HIGHLY ROUGHENED SURFACE This invention concerns protectively sheathed glassware containers and, more particularly, concerns glass receptacles which are so protected by an outer plastic envelope that substantially covers the exterior surface thereof.

As is well known in the trade, glassware is readily susceptible to breakage during handling and use. Further, the consequences of such breakage may be significantly aggravated if the contained product is carbonated or the container thereof is otherwise internally pressurized. Therefore, it has long been an objective of glassware manufacturers and users to minimize the haza rds of breakage by treating the exterior surface in numerous ways and by even adding protective overcoatings of various sorts thereto. These prior art approaches have, in fact, improved glassware standards and quality quite significantly since such have tended to effectively reduce the quantity of surface scratches and flaws in the ware and, of course, this reduction in the points of stress concentration enable the ware to retain its characteristic strength.

Such prior art treatments, for example, have included metal oxide, and combinations of thin film polyethylene coatings which provide good scratch and abrasion resistance to glassware thereby decreasing the surface flaws spoken of and likewise reducing the likelihood of breakage. Similarly, protective coatings having substantial thicknesses have been known for use on glass products. These, however, have been applicable only to specialized containers, for example, those employed in aerosol spray-type applications. Increased costs, production inefficiencies in capably coating ware in the quantities required, providing a coating of the quality capable of restraining and retaining glass upon fragmentation under pressure, and employment of such ware in conventional filling and handling equipment have theretofore been thought to make impossible the fruitful addition to the market of composite glass, plastic-protected ware.

Specific problems presented and overcome by this invention have been to provide the ware with a protective sheath or outer envelope'of a sufficient thickness and resilience to adequately restrain and retain the glass receptacle portion of a pressurized container against fragmentation. To economically accomplish this end, the volume of coating material must be minimized, yet the effective thickness thereof must be maximized to render the needed protection. Similarly, a consistently uniform, proper and good adhesion should be maintained between the glass receptacle portion and sheath portion of the container to provide the proper restraining effects. This diametrically opposed proposition, i.e., minimum material yet maximum protection, is satisfied by the novel construction of this invention.

shape-retaining, flexible resin which is not only able to restrain and retain fragments of the glass receptacle if the receptacle breaks out but also substantially alters the optical properties of the bottle.

extremely roughened sheath surface wherein there is at least a 20 percent deviation in thickness from its mean thickness. Such roughening, in particular, substantially reduces the light transmittance through the bottle. Thus, instead of exhibiting typical high transmittance, (values above 40 percent) bottles coated in accordance herewith restrict the transmitted light to below 20 percent.

Of course, the noted surface deviation creates voidlike areas that provide for increased shock protection while employing a minimum of resin material. Such re sult is obtained due to an increase in thickness adjacent the void-like areas which will bear the brunt of any physical abuse to which the container is subjected. Similarly, substantial portions of the coating are of a reduced thickness thus providing a material saving and creating the noted voids into which portions of the protruding material may flow upon impact. Thus, the effective thickness of the resin sheath is that of the protruding areas and the necessity of providing a uniform overall coating thickness which would employ substantially more resin is avoided.

To produce these desirable end results, it is preferred that the protrusions and void-like areas of the outer envelope or sheath deviate from the mean sheath thickness by about between 50 and 120 percent. This, in effect, further defines the respective dimensions of the protrusions and void therebetween. The novel plastic or resin covering or sheath also restrains and retains fragments of the glass receptacle should such receptacle be broken even when the container is pressurized to conditions approximating pounds per square inch. This effect is produced in accordance withthe invention, by providing the plastic covering or sheath of a flexible,'resilient resin which will stretch and expand rather than itself fragment in the event of receptacle failure. Such expansion of the covering before its own failure enables glass fragments to be restrained until the pressure within the receptacle escapes through initially formed, relatively small openings or fissures which may appear in the covering or sheath as it fails or until the pressure is otherwise relieved.

" FIG. 1 is a front elevational view of a container of the preferred embodiment;

FIG. 2 is a partial cross-sectional view of the container shown in FIG. 1 along line 22 thereof illustrating the invention; and

FIG. 3 is a series of curves showing the percentage of light transmission at various wave lengths for uncoated glass and glass coated with plastic in accordance with the invention.

In the preferred embodiment of the invention, container 10 as shown in FIGS. 1 and 2 comprises an inner glass receptacle or envelope l2 and an exterior outer sheath or envelope l4 comprised of a flexible shaperetaining resin contiguously covering a majority of the exterior surface 16 of receptacle l2. Sheath 14 is provided on its outer exposed surface 18 with a plurality of randomly positioned outwardly extending shock and light absorbing and reflecting protrusions 20. These are separated by depressions or void-like areas 22 which are believed to permit maximum deflection and expansion of protrusions 20 in a direction parallel to surface 16 upon receipt of excessive impacts. Accordingly, this maximized deflection is believed to increase the shock absorbing characteristics of sheath l4 and in addition,

reduces the amount of material needed for an effective Similarly, the roughening of surface 18 reduces the percentage of light transmitted through the bottle in accordance with the showing of FIG. 3. Thus, it can be seen that when an unpigmented resin is employed for the outer sheath I4 and a flint glass inner envelope is coated therewith a maximum of about percent light transmission will be expected at an 800 millimicron wave length. The transmission values are also substantially lower in the lower wave lengths of the visible spectrum and are, of course, even more suppressed when colored glass or resins are used. Likewise, it should be appreciated that light transmission will also vary with varying glass thicknesses and that the standard curves illustrated are based upon about an 0.080 ins. thickness.

Another indication of the quality of surface may be established by standard roughness tests (ASA B46.l 1962), for example. Using the techniques described in such standard and with a Type Q.C. Profilometer and Mototrace, it is preferred that a surface roughness value of between about 125 and 750 be measurable on bottles of this invention. Such being the case, one can also expect that the deviations from mean values as are established herein will be maintained, i.e., different measurement techniques of equivalent surface textures.

As was also set forth above, the protrusion/void distribution is random but it is expected that there will be about between 100 and 2,000 points of maximum and minimum outer envelope thickness per square inch of surface. It is, however, preferred that the distribution of same be retained in the range of between about 250 and 750 such points.

In the preferred embodiment, inner glass receptacle or envelope 12 has a wall thickness (Gx) of from about 0.03 to about 0.12 inches and the outer envelope 14 has a thickness of from about 0.004 to about 0.18 inches. This outer envelope preferably also is formed so that specific dimensional qualities are maintained. For example, it is considered appropriate to provide a mean envelope thickness value (Px) of about between 0.008 and 0.015 inches, the preferred range being between about 0.010 and 0.015 inches. Similarly, it is preferred that the protrusions and voids have maximum and minimum values above and below this base value on the order of 80 to 120 percent and approximately 50 to 95 percent respectively. In other terms, it is found that the preferred mean deviation above and below the mean thickness value .varies by at least per cent.

PREFERRED SHEATH OUTER SURFACE CHARACTERISTICS Px Sheath Pxl Mean Devia- Max. Max. Mean Thicktion above and Elevation Deflection ncss (in.) below Px above Px below Px 0.008 to The material of construction of sheath 14 may be any flexible and resilient resin which will stretch and expand rather than crack or fragment if inner receptacle 12 should break whether or not it is under internal pressure. Thermosetting resins such as flexible crosslinked urethane rubbers or others may be used; however, thermoplastic resins are preferred since they can be formed into coatings and films more easily and react in the manner above described and as is important in carrying out the invention.

Thermoplastic polymers of butadicne, acrylates, ethylene, propylene, styrene, vinyl, chloride, vinyl acetate, cellulose acetate, cellulose butyrate and cellulose propionate may be used. In addition, fluoroplastics, methyl pentenes, polyamides, phenoxy resin, polycarbonates, polyamides, polyphenylene oxides and polysulfone may be used.

The preferred plastics are inexpensive, have a relatively high tear strength, have high impact resistance, easilyform a contiguous film or coating and are flexible. Of those above mentioned, the preferred plastics are polyethylene, acrylonitrile-butadiene-styrene copolymers and impact polystyrene.

It is, of course, appreciated that a suitable means of application of the coating material or sheath 14 to inner glass receptacle 12 is a necessity and as examples it is suggested that any of the following may be employed depending upon the manufactures desired.

a. By spraying the thermoplastic material as a powder, optionally by an electrostatic spraying method, onto the hot external surface of the inner receptacle;

b. By dipping the inner receptacle, maintained at an appropriate-temperature, into a fluidized bed of the plastic material in powder form;

c. By dipping the inner receptacle, if desired while hot, into a molten bath of the plastic material or into a solution or a dispersion of such material, or

d. By any other material or providing a sleeve type coating to an inner glass receptacle known inthe art.

I claim:

l. A composite bottle adapted for the retention of fluid media and exhibiting a highly roughened exterior surface and comprising an inner glass envelope and an outer envelope comprising a single thermoplastic material surrounding the glass envelope and extending over substantially the entirety thereof, said outer envelope being further characterized in exhibiting an pproximate mean thickness of between about 0.010 inches and 0.015 inches, the maximum thickness being between about 0.008 inches and 0.015 inches in excess of the mean value and the minimum thickness being between about 0.005 inches and 0.009 inches less than the'mean value.

2. A composite bottle according to claim 1 wherein points of maximum and minimum outer envelope thicknesses are randomly scattered across said exterior surface, such scattering, however, occurring about between 250 and 750 points per square inch of surface, each of maximum and minimum thickness.

3. A composite bottle adapted for use in the retention of pressurized fluid media and exhibiting a highly roughened exterior surface and comprising a pressurizable inner glass envelope and an outer envelope comprising a single thermoplastic material surrounding said glass envelope and extending over substantially the entirety thereof, said outer envelope having a mean sidewall thickness of about between 0.010 and 0.015 inches, the exterior surface of said outer envelope being further characterized in that it exhibits a mean deviation both above and below the mean envelope thickness of at least about 20 per cent.

4. A composite bottle according to claim 3 wherein points of maximum and minimum outer envelope thickness are randomly scattered across said exterior surface, such scattering, however, occurring about between 250 and 750 points per square inch of surface, each of maximum and minimum thickness.

5. A composite bottle adapted for the retention of fluid media and exhibiting a highly roughened exterior surface and comprising an inner glass envelope and an outer envelope comprising a single thermoplastic material surrounding the glass envelope and extending over substantially the entirety thereof, said outer envelope being further characterized in exhibiting an approximate mean thickness of between about 0.0l0 inches and 0.015 inches, the maximum thickness being beabout 5 and 20 percent respectively. 

2. A composite bottle according to claim 1 wherein points of maximum and minimum outer envelope thicknesses are randomly scattered across said exterior surface, such scattering, however, occurring about between 250 and 750 points per square inch of surface, each of maximum and minimum thickness.
 3. A composite bottle adapted for use in the retention of pressurized fluid media and exhibiting a highly roughened exterior surface and comprising a pressurizable inner glass envelope and an outer envelope comprising a single thermoplastic material surrounding said glass envelope and extending over substantially the entirety thereof, said outer envelope having a mean sidewall thickness of about between 0.010 and 0.015 inches, the exterior surface of said outer envelope being further characterized in that it exhibits a mean deviation both above and below the mean envelope thickness of at least about 20 per cent.
 4. A composite bottle according to claim 3 wherein points of maximum and minimum outer envelope thickness are randomly scattered across said exterior surface, such scattering, however, occurring about between 250 and 750 points per square inch of surface, each of maximum and minimum thickness.
 5. A composite bottle adapted for the retention of fluid media and exhibiting a highly roughened exterior surface and comprising an inner glass envelope and an outer envelope comprising a single thermoplastic material surrounding the glass envelope and extending over substantially the entirety thereof, said outer envelope being further characterized in exhibiting an approximate mean thickness of between about 0.010 inches and 0.015 inches, tHe maximum thickness being between about 80 and 120 percent in excess of the mean value and the minimum thickness being between about 50 and 95 percent less than the mean value.
 6. A composite bottle adapted for the retention of fluid media and exhibiting a highly roughened exterior surface and comprising an inner glass envelope and an outer envelope of thermoplastic material surrounding the glass envelope and extending over substantially the entirety thereof, said bottle being further characterized in that the percentage of transmitted visible light in the range of 500 and 800 millimimicrons, varies between about 5 and 20 percent respectively. 